Glue product and method of preparing the same



iatented Jan. 31, 1933 UNrrs r EDWARD I. CHRISTOPHER AND FRANK L. DE BEUKELAEB, OF CHICAGO, ILLINOIS ASSIGNORS TO SWIFT & COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF HILINOIS GLUE PRODUCT AND METHOD OF PBEEAEWG THE SAME Ho Drawing. Application filed July 13,

an open kettle or under steam pressure, either with or without previous treatment with acid. It is a further object of this invention to provide a process of producing a glue of the above described type which oiiers the econom- 29 ic advantage of lower cost of production and superior quality by the removal of nonadhesive material from the glue solutions.

It is a further object of this invention to provide a glue possessing the above stated advantages, made in accordance with the process of this invention.

It is a further object to provide a trans-' parent bone glue or gelatine that can be blended or mixed with a hide glue or hide gelatine and still maintain the resulting mixture as a transparent solution.

To assist in the understanding of this invention, it is deemed advisable to point out that ordinary commercial glue is produced by cooking animal bones either in an open kettle, or in some cases, under steam pressure, either with or without previous treatment with acid. As a result, the glue or gelatine contained in the bones is dissolved, and a solution produced which is'opalcscent or opaque. The product thus derived is serviceable in many uses, but in other instances, it is desirable to obtain a transparent clear bone glue or gelatine.

It has been discovered that the opaque or 1931. Serial No. 550,619

opalescent appearance of the glue solution is due to the presence of certain non-adhesive materials, the elimination of which not 0111 improves the quality of the glue from the ad hesive standpoint, but also renders it clear and transparent, which isimportant where a clear glue is required and as an enhancement of the marketability of the product.

It is well known that the treatment of glue solutions with an acid such as phosphoric acid or sulphurous acid will cause the alkaline earths present in the solution to precipitate out at a pH 7 .0 or thereabouts. If the acidity of the solution is adjusted to the neighborhood of pH 5.0 or lower, the alkaline earth so salts go back into solution. The alkaline earths have the effect of rendering dried glue opaque and, therefore, common practice in the treatment of glue liquors calls for treatingthe liquor with phosphoric acid or sule5 phurous acid to adjust the acidity of the liquor to a pH of 7 .0 which is most conveniently done in practice by resorting to litmus as the indicator. We have found that the alkaline earths which are thus removed as a precipi- 7o tate at a pH of 7.0 have no appreciable ef feet on the transparency or opacity of liquid glue which is the product of the present invention. However, there are present in all glue liquors, certain little understood organic substances which do not seem to efi'ect the transparency or opacity of dried glue and are, therefore, not a factor for consideration in the'manufacture of dried glue, which do adversely afl'ect the transparency of so liquid glue. The present invention contemplates the removal of these substances without the removal of the alkaline earths and as will be pointed out in this specification more in detail, this is accomplished by adjusting the acidity of the glue liquor solution to a pH of 5.0 or lower at which degree of acidity, determined in practice by the use of methyl red as an indicator, the organic substances which tend to cloud the Qt liquid glue flocculate out and any .alkaline earths which have commenced precipitation go back into solution since these substances are soluble at the degree of acidity indicated by a pH of 5.0 or lower.

Accordingly, this invention is directed to a process by which the non-adhesive materials are removed and the glue is rendered transparent and clear and of better adhesive quality, and also to the glue product resulting therefrom.

t has been found that the non-adhesive materials may be removed by treating the bone glue or bone gelatine solution prepared as above described, with acids or acid reacting salts, or acid reacting or producing substances, of such character and in such quantity that the acidity of the bone glue or bone gelatine solution is adjusted to a pH of substantially 5.0 or lower. As a matter of example, it is found that hydrochloric, sulphuric, nitric, phosphoric, tartaric, oxalic, or sulphurous acids serve well in this use, but other acids or acid reacting salts, or acid reacting or producing substances, or mixtures of any of the above named substances, may be used. For instance, it has been found that hydrogen peroxide may be substituted for any of the above named acids for the production of the same results. The reason for this is not clearly understood, but it is considered that hydrogen peroxide, which is a strong oxidizing agent, acts in the presence of the glue, which is an amphoteric substance, to produce a pH of approximately 5.0 or lower.

After the pH is adjusted to approximately 5.0 or lower, flocculation takes place, and the flocculated material may then be separated from the remaining clear liquid by any suitable method, such as draining off the clear liquid, centrifuging the solution, or by any other means known to those skilled in the art for removing suspended materials from liquids.

Thereafter, the clear bone glue or gelatine solution may be concentrated, and if desired, dried. It is found that the dried product when dissolved in water, again produces a transparent clear solution. The applicants have discovered that ordinary solutions of bone glue or gelatine not treated in accordance with this clarifying process, even though filtered as dilute solutions, will become opaque when concentrated.

The clarifying process here described produces a thinner or less viscous glue than the corresponding unclarified glue when both have the same setting point. This fact makes for advantage for several reasons; first, at equal viscosities more glue solids can be applied to objects and consequently the time required for the glue to set and for the water to evaporate is decreased, thereby effecting a saving 1n power in cases where evaporatlon 15 hastened mechanically. Secondly, the thinvof being more readily soluble in water than the corresponding unclarified bone glue, which fact makes it possible to disperse the clarified glue in cold water within a few minutes.

As above pointed out, in addition to improving the quality by the elimination of the non-adhesive material, it is found that the clarified glue can be made into a liquid glue with considerably less liquefying reagent than is required for the unclarified glue. This fact adds to the economic advantage, in lowering the cost of production of liquid glue due by the saving of the cost in a liquefying agent, which is quite substantial in producing large quantities of this product.

The transparent glue product resulting from this process can be mixed or blended with a hide glue or gelatine with the result that a transparent clear product results.

We claim:

1. The process of producing a transparent clear bone glue or bone gelatine solution, which consists in treating ordinary bone glue or bone gelatine solutions with acids, acid reacting salts, acid producing substances or mixtures thereof, so that the acidity of the bone glue or bone gelatine solution is adjusted to substantially a pH of 5.0 or lower, at which degree of acidity the alkaline earths are not substantially affected, and light scattering 7 organic material present in colloidal suspension fiocculates out and thereafter removing the flocculated material formed.

2. The process of producing a transparent clear bone glue or bone gelatine solution, which consists in treating ordinary bone glue or bone gelatine solutions with acids, acid reacting salts, acid producing substances or mixtures thereof, so that the acidity of the bone glue or bone gelatine solution is adjusted to substantially a pH of 5.0 or lower, at which degree of acidity the alkaline earths are not substantially affected, and light scattering organic material present in colloidal suspension fiocculates out thereafter removing the flocculated material formed, and mixing or blending the resulting clear solution with hide glue or hide gelatine for the production of a clear transparent final product.

3. A process which consists in treating ordinary bone glue or bone gelatine solution with an acid substance sufficient to adjust the solution to a pH of substantially 5.0 or lower at which degree of acidity the alkaline earths are not substantially affected, and light scattering organic material present in colloidal suspension fiocculates out.

4. A glue product produced by the method set forth in claim 1.

5. A glue product produced by the method set forth in claim 2.

set forth in claim 3.

Signed at Chicago, in the county of Cook and State of Illinois, this 10th day of July, 1931.

EDWARD F. CHRISTOPHER. FRANK L. DE BEUKELAER. 

